A spectroscopic study of mass outflows in the interacting binary RY scuti

Erika D. Grundstrom, Douglas R. Gies, Todd C. Hillwig, M. Virginia McSwain, Nathan Smith, Robert D. Gehrz, Otmar Stahl, Andreas Kaufer

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The massive interacting binary RY Scuti is an important representative of an active mass-transferring system that is changing before our eyes and which may be an example of the formation of a Wolf-Rayet star through tidal stripping. Utilizing new and previously published spectra, we present examples of how a number of illustrative absorption and emission features vary during the binary orbit. We identify spectral features associated with each component, calculate a new, double-lined spectroscopic binary orbit, and find masses of 7.1 ± 1.2 M for the bright supergiant and 30.0 ± 2.1 M for the hidden massive companion. Through tomographic reconstruction of the component spectra from the composite spectra, we confirm the O9.7 Ibpe spectral class of the bright supergiant and discover a B0.5 I spectrum associated with the hidden massive companion; however, we suggest that the latter is actually the spectrum of the photosphere of the accretion torus immediately surrounding the massive companion. We describe the complex nature of the mass-loss flows from the system in the context of recent hydrodynamical models for β Lyr, leading us to conclude RY Scuti has matter leaving the system in two ways: (1) a bipolar outflow from winds generated by the hidden massive companion, and (2) an outflow from the bright O9.7 Ibpe supergiant in the region near the L2 point to fill out a large, dense circumbinary disk. This circumbinary disk (radius ≈1 AU) may feed the surrounding double-toroidal nebula (radius ≈2000 AU).

Original languageEnglish (US)
Pages (from-to)505-519
Number of pages15
JournalAstrophysical Journal
Issue number1 I
StatePublished - 2007


  • Binaries: close
  • Binaries: eclipsing
  • Circumstellar matter
  • Stars: individual (RY scuti)
  • Stars: mass loss
  • Stars: winds, outflows


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